Fire insulation edge reinforcements for structural members

ABSTRACT

Fire insulation reinforcements protect structural members from exceedingly high temperatures during fires. The reinforcements are supported on the flange sections of structural members as well as flat surfaces to effectively hold the fireproofing coating in place during fires so as to better insulate the flat surfaces and outer edges from damage during fires.

United States Patent [191 Billing et a1.

[ Oct. 21, 1975 1 1 FIRE INSULATION EDGE REINFORCEMENTS FOR STRUCTURALMEMBERS [75] Inventors: Rudolph W. Billing, Littleton;

George K. Castle, Chelmsford, both of Mass.

[73] Assignee: Avco Corporation, Cincinnati, Ohio [22] Filed: June 13,1974 [21] Appl. No.: 478,844

Related US. Application Data [63] Continuation-impart of Ser. No.454,077, March 25,

1974, abandoned.

[52] US. Cl. 52/347; 52/454; 52/515;

52/647; 52/729 [51] Int. Cl. E04F 13/06; E04C 3/293 [58] Field of Search52/232, 729, 515, 516,

[56] References Cited UNITED STATES PATENTS 670,938 4 1901 Rapp 52/3441,860,205 5/1932 Schenker 52/647 X 1,983,994 12/1934 Raynor 52/4541,988,081 1/1935 Kemper 52/647 2,166,798 7/1939 Cote 52/729 X 2,213,6039/1940 Young et a1. 52/725 X 2,702,932 3/1955 Woodson 52/725 X 3,516,2136/1970 Sauer 52/725 3,570,208 3/1971 Sei Niker et al.... 161/4033,798,867 3/1974 Starling 52/724 FOREIGN PATENTS OR APPLICATIONS 130,8563/1929 Switzerland 52/647 551,262 3/1923 France 52/725 OTHERPUBLICATIONS Architectural Engineering pp. 161 163 Tomasetti, NewApproach to the Fire Protection of Steel, Sept, 1972.

Primary ExaminerErnest R. Purser Assistant ExaminerLeslie A. BraunAttorney, Agent, or Firm-Charles M. Hogan, Esq.; Abraham Ogman, Esq.

[57] ABSTRACT Fire insulation reinforcements protect structural membersfrom exceedingly high temperatures during fires. The reinforcements aresupported on the flange sections of structural members as well as flatsurfaces to effectively hold the fireproofing coating in place duringfires so as to better insulate the flat surfaces and outer edges fromdamage during fires.

6 Claims, 11 Drawing Figures a Patent Oct.21, 1975 Sheet10f3 3,913,290

RECORDED TEMPERATURE IN F US. Patent Oct. 21, 1975 Sheet2of3 FIG.5

TEMPERATURE MEASUREMENT PLAN: I I I I TING I INSULATED REINFORCED EDGE 8(ALL FOUR) TIME- IN MINUTES g/24B RIG. 7 I

22 FIG-.8 |8C IBDW 9 i i 1" US. Patent Oct. 21, 1975 Sheet 3 of33,913,290

FIGJI 48 FIG. IO

FIRE INSULATION EDGE REINFORCEMENTS FOR STRUCTURAL MEMBERS Thisapplication is a continuation-in-part of our copending US. patentapplication Ser. No. 454,077, filed Mar. 25, 1974, now abandoned.

BACKGROUND OF THE INVENTION This invention relates generally to fireprotective coatings and more particularly to a wire mesh and fireproofcoating to provide a fire insulation reinforcement for structuralmembers.

Structural members, such as steel beams, walls, containers and the like,are often fireproofed with coatings to protect against the heat producedin an unplanned fire. Without this protection, the member would soonreach temperature levels where the accompanying loss in strength willresult in the structural member failing under load. Most constructionstructural members have flange edges such as I beams, H beams, channelsand angles. These edges are the most difficult parts of the member toprotect against heating because the flow of heat from the fire comes inthree directions (top, bottom, and perpendicular to the edge) instead ofthe two directions possible on flat planar surfaces. The flow of heat isrepresented in FIG. 1 by the arrows.

Some thin coatings presently used for fire protection are intumescent innature. These coatings swell into a carbonaceous foam when heated whichinsulates against the fire. However, during fires these materials maylose their bonding properties and sections of the material may fall fromthe member thereby exposing the bare member to the fire. This type ofcoating poses even greater problems in providing protection to the edgemember because the intumescence takes place in only one direction, i.e.,perpendicular to the coated surface and thus large cracks or fissuresare likely to occur in the foamed material at the edges of the steelflanges. No lateral intumescence really occurs and when the foamintumesces outward, the surface area does not change, forcing fissuresto occur at the surface.

The primary method used for steel member edge protection hastraditionally been to cover the edges with sufficient coating materialto overcome the problem. Often during fire tests (ASTM E-l19) of suchprotection systems, the temperature level recorded in the edges of thetest specimen was the highest, and hence controlled the length of thetest.

It is very difficult to apply extra fireproofing material to the edgesof structural members whether the material is cast into place (concrete)or sprayed in place (cementitious mixtures, fibers, or intumescentmastics). The reason is because of the inconvenience of the shapesinvolved (casting) and the difficulty of building up a localized thinstrip (spraying) along the edge. Rather, the practice has been touniformly apply more material to the entire perimeter of the structuralshape to insure that the edges are protected. A disadvantage of thismethod is that it causes more material to be used than necessary,increases weight, and increases costs (both material and spray time).

Accordingly, it is an object of this invention to pro-- vide fireinsulation reinforcements which will provide reliable thermal protectionto structural members, be easy to apply, and thoroughly reinforce theentire fireproofing coating both inthe virgin state and during a firewhen the intumesced char layer forms.

A further object of this invention is to provide an insulated edgereinforcement which gives better thermal performance of fireproofedstructural members in a fire.

A still further object of this invention is to provide insulatedreinforcements which permit reduced overall coating thickness and wastethrough eliminating overspray from trying to build up fireproofingcoating thicknesses on the edges of the flanges.

And yet another object of this invention is to provide an insulatedreinforcement which increases reliability and safety through thereinforcement of the fireproofing coating thereby preventing earlybonding failures of the fireproofing material in a fire.

SUMMARY OF THE INVENTION This invention provides an insulatedreinforcement for use on structural members. The reinforcement issupported on the structural member and the fireproofing material placedthereabout so as to protect and insulate the surface and respectiveedges of the members from damage due to heat during unplanned fires. Thereinforcement secures an insulation strip against the end of thestructural flange. Fireproofing material is applied over the mesh andinsulation strip in a thickness sufficient to protect the flanges andwebs of the structural member.

Other objects, details, uses and advantages of this invention willbecome apparent. as the following description of the exemplaryembodiments thereof presented in the accompanying drawings proceeds.

BRIEF DESCRIPTION OF THE DRAWINGS V securing an open leg insulated edgereinforcement to a DESCRIPTION OF ILLUSTRATED EMBODIMENTS Reference isnow made to FIG. 1 of the drawings which illustrates a typicalstructural member 10, such as a structural steel I-beam. It is seen thatthe I-beam 10 includes a plurality of flange sections 12 having endedges 14 and 16. As previously indicated, the direction of the flow ofheat from a fire is indicated by the ar rows. It can be seen that theweb 11 and flange 12 each have two-directional heating, i.e.,perpendicular to the structural surfaces. The end or edge of the flange12 is seen to have three-dimensional heating, the third direction beingperpendicular to the edge of the flange.

The insulated edge reinforcement system 20 is shown in two basic formsin FIGS. 2 and 3. The FIG. 3 form has a precast edge of coating materialor a steel edge and the FIG. 2 form does not. Both forms perform thesame functions, however.

Referring now to FIG. 2, the edge reinforcement 20 is constructed of ameshlike member such as wire mesh 18. The wire mesh 18 is formed in apress brake or similar machine to the shape required for the member tobe protected. Welded wire mesh is preferred and may either be with orwithout galvanizing. The mesh size may be any suitable opening fromone-fourth inch to 1 inch or greater. The wire diameter should be smallenough to reduce cost and permit easy forming, but large enough to holdthe formed shape firmly. One edge reinforcement having excellentfireproofing capabilities was constructed of one-half inch mesh and 19gauge wire.

Sheet insulation 22 is sliced or cut into strips and laid into theformed wire mesh 18. Any suitable fibrous insulation such as U.S. GypsumThermafiber may be used. It is noted that board insulations will alsowork. A practical limit on the thermal conductivity for the insulationused is approximately 0.2 Btu/ft-hr-F. The size of the insulation strip22 is preferably at least twice the flange 12 thickness in depth andpreferably at least equal to the flange thickness in thickness.

In the precast form of FIG. 3, the formed wire 18A with theinsulation22A in place is placed edge first into a mold (not shown)containing the casting material. The edge reinforcement A is left in themold until hardening of the edge material 24 occurs. The reinforcementwith the precast edge 24 is then stripped from the mold and is ready forshipping and installation. For some cases, a metal edge 24 may bestapled or welded on the reinforcement 20A in place of the precast edge.

The reinforcements 20 may be made with either open legs or closed legsduring the forming operation. The legs are considered as that part ofthe wire mesh which extends inwardly from the flange edge to the web. Ifa closed leg form is used, the insulated reinforcement 20 is merelyslipped over the flange by hand after slightly spreading the legs apart.It is held in place on the flange by the spring tension in the wire legsuntil the fireproofing coating is sprayed over the system. If the openleg form is used, the reinforcement 20 is slipped on the flange and acrimping tool 26 is used to tighten the wire against the flange surfaceas shown in FIG. 4.

The crimping tool 26 is seen to comprise a pair of forcing members orhandles 28 and 30 pivotally connected together at 32. The handle 28includes an outer peripheral shoulder 34 and a vertically projectingshoulder 36. The peripheral shoulder 34 acts against one leg of the wiremesh 18 and holds the mesh 18 against the flange 12. The shoulder 36abuts against the precast edge 24 along the exterior side of theinsulation strips 22. One end or shoulder 38 of the handle 30 engagesthe opposite leg of the wire mesh 18. Thus, when the handles 28 and 30are pressed or forced together, force is applied through the shoulders34 and 38 to bend the open legs of the wire mesh 18 into a clampingcondition relative to the flange 12.

After the insulated reinforcement 20 is in place, any suitablefireproofing material (not shown) is applied over the reinforcement 20in a thickness which is sufficient to protect the flanges and webs ofthe structural member 10. These thicknesses are in practice determinedby actual fire tests (i.e., ASTM E-119). However, the edges 14-16 of thereinforced flange do not now have to be built up in thickness; theymerely have to be covered with enough material to produce a neatcontinuous coating.

If an unplanned fire should occur, the insulated reinforcement 20 worksin the following manner. First of all, the presence of the insulation 22inside the wire mesh 18 retards the perpendicular flow of heat into theedge of the flange 12, thus keeping it cooler for a longer period oftime. The wire mesh 18 itself holds the fireproofing material togetherall around the edges 14-16 and flange 12 as the material decomposes,intumesces, etc. This is especially important since the steel primersand paints which the coatings are applied over usually lose theirbonding strength at temperature levels far below that which the steelitself may be safely allowed to reach, approximately 1000F. In thepresence of bonding strength failure, the fireproofing mate rial hasnothing holding it onto the steel except its own structural integrity.The wire reinforcement 18 provides this integrity if needed.

Finally, if an intumescent coating is used, there is a very highpossibility of fissures and cracks forming at the edges of the flangesand uncovering bare steel. Should this happen, up to a 30 percentincrease in heat flux into the flange may occur if only 1 percent of thesteel surface is exposed. However, with the reinforcement member 20,instead of these fissures uncovering bare steel in this area, only theinsulation 22 will be exposed and the heat transfer to the edge of thesteel flange will be many times less than if the steel itself wereexposed. Naturally, this permits much better fire performance of theoverall coating system. Another advantage of the mesh 18 is that iffissures form on the flange surfaces, they will stop when the wire mesh18 is reached. The material under the mesh swells beneath it andprovides some protection to the steel directly below the fissure.

FIG. 5 represents a comparison of the edge temperature versus the flangecenter and web temperatures using the edge reinforcement of thisinvention. In this test, a 10WF49 beam was reinforced as hereinabovedescribed and coated with an intumescent fire protective coatingdeveloped at'Avco Systems Division, in Lowell, Mass, and marketed underthe name AVCO FM 59. The test was run in an environment in which thefurnace temperature was 1950F., the radiant heat flux was 16.2 Btu/ft-sec. and the convective heat flux was l-2 Btulft -sec. Temperatureswere measured in the web, flange web joint and at the edges of the topand bottom flanges and are respectively designated on the chart bytriangle, square, circleand hexagon. The effectiveness of the edgereinforcement protection is demonstrated by the overall fire performanceof the beam and by the fact that the beam remained fairly uniform intemperature distribution throughout the test.

same protection as the rest of the beam.

Referring now to FIGS. 6-9, it is seen that the edge reinforcementmember of this invention may be formed in varying shapes depending onthe desired end use. Different wire meshes may be employed, as well asdifferent types of insulation. The insulation can be placed on the edgeof the flange by any suitable means such as contact cement and the wireslipped over the insulation later. If a precast or metal edge is used,the type of material can be varies as long as it bonds well to thefireproofing material which is applied over it. The actual shape of thewire mesh will depend on the end use.

As particularly seen in FIG. 6, the wire mesh 18B is seen to be formedin a T-shape over the end of the insulation 22. FIG. 7 shows the T-shapewire mesh 18B being utilized with a precast edge or metal edge 24B. Theedge 24B conforms to the T end of the wire mesh 18B and is held thereby.

FIG. 8 represents another embodiment in which the wire mesh 18C isformed with an enlarged or bulb portion 40. The purpose of the bulb isto permit firm anchoring of a maximum amount of fireproofing materialunder the mesh near the flange edge.

The embodiment of FIG. 9 is very similar to the FIG. 2 embodiment. Thedifference in this instance is that the wire mesh 18D is formed withsurface standoff dimples 42. Thus, when the mesh 18D is placed over theflange, the dimples 42 will engage the flange with the majority of thewire mesh 18 being supported away from the surface of the flange. Thispermits better anchoring of the fireproofing material under the mesh.

The fire insulation reinforcement of this invention is also applicablefor use on large flat surfaces such as walls, large cylindricalcontainers and the like. Referring now to FIGS. 10 and 11, a fragmentaryview of a wall 44 is seen to be fire protected by a fire insulationreinforcement designated generally as 46. The fire insulationreinforcement 46 is formed in the same manner as previously described.In the case where large walls or the like are to be protected, the wiremesh 48 is mechanically attached to the wall by any suitable means. Asan example, if the wall 44 is of steel plate, the wire mesh 48 may besecured thereto by spot welds 50. If the member will not support a weld,suitable means, such as support pins or the like, may be utilized tosupport the wire mesh in place. The fireproof coating 52 is then appliedover the wire mesh 48 such that the wire mesh is in effect encased inthe fireproof material 52. Hence, if a fire should occur the material 52will intumesce. When the material intumesces, the fireproofing materialvery often will lose the bonding capabilities it has with the structuralmember. In addition, fissures may occur in the material. If the wiremesh 48 was not used, sections of the fire protective material mightfall off thereby exposing the structural member. However, the wire mesh48 holds the fireproofing material 52 in place even though the materialhas lost its bonding effect. Similarly, if a fissure should develop, thefissure would be stopped in the wire mesh level and would not extend tothe structural member.

It is seen that the fireproof reinforcements of this invention overcomethe disadvantages of prior methods of fireproofing structural members.The fireproof reinforcement of this invention is simple in structure,easily applied to the flange portions and provides effectivefireproofing when used with the fireproofing material, such asintumescent coatings and the like. Accordingly, it is seen that theobjectives hereinbefore set forth have been accomplished.

While present exemplary embodiments of this invention have beenillustrated and described, it will be recognized that this invention maybe otherwise variously embodied and practiced by those skilled in theart.

What is claimed is:

1. In combination with a structural member having flange portionsterminating in an edge susceptible of receiving heat from threedirections, a fire insulation structure comprising:

insulation means secured in an abutting relationship to said edge, theinsulation means having thickness equal to the thickness of said edgeand a depth greater than the thickness of said edge; and

a mesh means around the periphery of said insulation means, said meshmeans having leg portions extending beyond the insulation means, saidleg portions being engageable with the flange portions of the structuralmember to secure said insulation means in an abutting relationship withthe edge of the flange wherein a fireproof coating is applied over theentire structural member and mesh means thereby substantially reducingthe amount of heat flow directed to the end and edges of the flangeduring fire conditions.

2. The structure set forth in claim 1 in which said mesh means is a wiremesh wherein said wire mesh holds the fireproofing coating together allaround the edge and flange as the coating decomposes.

3. The structure as set forth in claim 2 further comprising an edgemember secured to the exterior of said wire mesh and insulation means soas to provide an easily fireproofable edge surface for the structuralmemher.

4. The structure defined in claim 2 wherein said structural memberincludes a flange terminating in said end and edge to which theinsulation is secured.

5. The structure as set forth in claim 4 in which the leg portions ofsaid wire mesh frictionally engage opposite surfaces of the portionsflange thereby holding said insulation means in place against the flangeedge.

6. In a combination with a structural member having an end terminatingin an edge susceptible of receiving heat from three directions, andhaving a fireproof coating over its entire surface, a fire insulationstructure comprising:

insulation means interposed between the fireproof coating and said edgein an abutting relationship to said edge, the insulation means having athickness equal to the thickness of said edge, and a depth greater thanthe thickness of said edge, wherein said insulation reducing the amountof heat flow directed to said edge.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. I 3,913, 2.90

DATED October 21, 1975 INVEN IOR(S) Rudolph W. Billing and George K,Castle It is certified that error appears in the above-identified patentand'that said Letters Patent are hereby corrected as shown below:

Column 3, line 4, please change "three-dimensional" tothree-directional",

Column 6, line 47, please change "portions flange to "flange portions.

Signed and Sealed this ninth Day of March 1976 [SEAL] A ttes t:

1. In combination with a structural member having flange portionsterminating in an edge susceptible of receiving heat from threedirections, a fire insulation structure comprising: insulation meanssecured in an abutting relationship to said edge, the insulation meanshaving thickness equal to the thickness of said edge and a depth greaterthan the thickness of said edge; and a mesh means around the peripheryof said insulation means, said mesh means having leg portions extendingbeyond the insulation means, said leg portions being engageable with theflange portions of the structural member to secure said insulation meansin an abutting relationship with the edge of the flange wherein afireproof coating is applied over the entire structural member and meshmeans thereby substantially reducing the amount of heat flow directed tothe end and edges of the flange during fire conditions.
 2. The structureset forth in claim 1 in which said mesh means is a wire mesh whereinsaid wire mesh holds the fireproofing coating together all around theedge and flange as the coating decomposes.
 3. The structure as set forthin claim 2 further comprising an edge member secured to the exterior ofsaid wire mesh and insulation means so as to prOvide an easilyfireproofable edge surface for the structural member.
 4. The structuredefined in claim 2 wherein said structural member includes a flangeterminating in said end and edge to which the insulation is secured. 5.The structure as set forth in claim 4 in which the leg portions of saidwire mesh frictionally engage opposite surfaces of the portions flangethereby holding said insulation means in place against the flange edge.6. In a combination with a structural member having an end terminatingin an edge susceptible of receiving heat from three directions, andhaving a fireproof coating over its entire surface, a fire insulationstructure comprising: insulation means interposed between the fireproofcoating and said edge in an abutting relationship to said edge, theinsulation means having a thickness equal to the thickness of said edge,and a depth greater than the thickness of said edge, wherein saidinsulation reducing the amount of heat flow directed to said edge.